A decade-long trends in ligamentum flavum hypertrophy among spinal stenosis patients: A comparative analysis of incidence and patterns.

Introduction: Lumbar spinal stenosis (LSS) is a prevalent degenerative condition, with ligamentum flavum hypertrophy (LFH) contributing significantly to neural compression. Despite its clinical importance, few studies have evaluated longitudinal trends in LFH. This study investigates the temporal progression and demographic associations of LFH over the past decade. Methods: This retrospective cohort study included adult patients undergoing surgery for LSS at a tertiary academic center during two periods: 2013-2017 and 2018-2023. Exclusion criteria included prior spinal surgery, trauma, malignancy, or inadequate imaging. Two radiologists reviewed axial MRI images to measure ligamentum flavum thickness (≥4 mm indicated hypertrophy). Demographic data and coexisting spinal conditions were also recorded. Results: A total of 202 patients were analyzed-98 from the initial and 104 from the later period. LFH prevalence rose from 24.5 % to 44.7 % over time. Patients aged ≥60 demonstrated significantly higher LFH rates in both periods (p = 0.004). Although female predominance persisted, it declined from 71.4 % to 55 %. LFH was most commonly associated with disc bulging, particularly at the same spinal level. Multilevel LFH increased from 25 % to 44.1 %, though L4-L5 remained the most affected segment. Conclusion: The incidence of LFH has increased substantially over the past decade, particularly among older adults. Given its role in LSS pathogenesis, greater attention to LFH in imaging and surgical planning is warranted. Further research is needed to clarify its etiology and guide effective management strategies.